From: Hannes Reinecke <hare@suse.de>
To: Pankaj Raghav <kernel@pankajraghav.com>,
Matthew Wilcox <willy@infradead.org>
Cc: linux-xfs@vger.kernel.org, linux-fsdevel@vger.kernel.org,
gost.dev@samsung.com, chandan.babu@oracle.com, mcgrof@kernel.org,
djwong@kernel.org, linux-mm@kvack.org,
linux-kernel@vger.kernel.org, david@fromorbit.com,
akpm@linux-foundation.org, Pankaj Raghav <p.raghav@samsung.com>
Subject: Re: [PATCH v3 04/11] readahead: rework loop in page_cache_ra_unbounded()
Date: Tue, 26 Mar 2024 11:55:06 +0100 [thread overview]
Message-ID: <2b1a2ded-d26f-4c9e-bd48-2384b5a7c2c9@suse.de> (raw)
In-Reply-To: <1a4a6ad3-6b88-47ea-a6c4-144a1485f614@pankajraghav.com>
On 3/26/24 11:06, Pankaj Raghav wrote:
> On 26/03/2024 11:00, Hannes Reinecke wrote:
>> On 3/26/24 10:44, Pankaj Raghav wrote:
>>> Hi Hannes,
>>>
>>> On 26/03/2024 10:39, Hannes Reinecke wrote:
>>>> On 3/25/24 19:41, Matthew Wilcox wrote:
>>>>> On Wed, Mar 13, 2024 at 06:02:46PM +0100, Pankaj Raghav (Samsung) wrote:
>>>>>> @@ -239,8 +239,8 @@ void page_cache_ra_unbounded(struct readahead_control *ractl,
>>>>>> * not worth getting one just for that.
>>>>>> */
>>>>>> read_pages(ractl);
>>>>>> - ractl->_index++;
>>>>>> - i = ractl->_index + ractl->_nr_pages - index - 1;
>>>>>> + ractl->_index += folio_nr_pages(folio);
>>>>>> + i = ractl->_index + ractl->_nr_pages - index;
>>>>>> continue;
>>>>>> }
>>>>>> @@ -252,13 +252,14 @@ void page_cache_ra_unbounded(struct readahead_control *ractl,
>>>>>> folio_put(folio);
>>>>>> read_pages(ractl);
>>>>>> ractl->_index++;
>>>>>> - i = ractl->_index + ractl->_nr_pages - index - 1;
>>>>>> + i = ractl->_index + ractl->_nr_pages - index;
>>>>>> continue;
>>>>>> }
>>>>>
>>>>> You changed index++ in the first hunk, but not the second hunk. Is that
>>>>> intentional?
>>>>
>>>> Hmm. Looks you are right; it should be modified, too.
>>>> Will be fixing it up.
>>>>
>>> You initially had also in the second hunk:
>>> ractl->index += folio_nr_pages(folio);
>>>
>>> and I changed it to what it is now.
>>>
>>> The reason is in my reply to willy:
>>> https://lore.kernel.org/linux-xfs/s4jn4t4betknd3y4ltfccqxyfktzdljiz7klgbqsrccmv3rwrd@orlwjz77oyxo/
>>>
>>> Let me know if you agree with it.
>>>
>> Bah. That really is overly complicated. When we attempt a conversion that conversion should be
>> stand-alone, not rely on some other patch modifications later on.
>> We definitely need to work on that to make it easier to review, even
>> without having to read the mail thread.
>>
>
> I don't know understand what you mean by overly complicated. This conversion is standalone and it is
> wrong to use folio_nr_pages after we `put` the folio. This patch just reworks the loop and in the
> next patch I add min order support to readahead.
>
> This patch doesn't depend on the next patch.
>
Let me rephrase: what does 'ractl->_index' signify?
From my understanding it should be the index of the
first folio/page in ractl, right?
If so I find it hard to understand how we _could_ increase it by one;
_index should _always_ in units of the minimal pagemap size.
And if we don't have it here (as you suggested in the mailthread)
I'd rather move this patch _after_ the minimal pagesize is introduced
to ensure that _index is always incremented by the right amount.
Cheers,
Hannes
next prev parent reply other threads:[~2024-03-26 10:55 UTC|newest]
Thread overview: 38+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-03-13 17:02 [PATCH v3 00/11] enable bs > ps in XFS Pankaj Raghav (Samsung)
2024-03-13 17:02 ` [PATCH v3 01/11] mm: Support order-1 folios in the page cache Pankaj Raghav (Samsung)
2024-03-13 17:02 ` [PATCH v3 02/11] fs: Allow fine-grained control of folio sizes Pankaj Raghav (Samsung)
2024-03-25 18:29 ` Matthew Wilcox
2024-03-26 8:44 ` Pankaj Raghav (Samsung)
2024-03-13 17:02 ` [PATCH v3 03/11] filemap: allocate mapping_min_order folios in the page cache Pankaj Raghav (Samsung)
2024-03-15 13:21 ` Pankaj Raghav (Samsung)
2024-03-13 17:02 ` [PATCH v3 04/11] readahead: rework loop in page_cache_ra_unbounded() Pankaj Raghav (Samsung)
2024-03-25 18:41 ` Matthew Wilcox
2024-03-26 8:56 ` Pankaj Raghav (Samsung)
2024-03-26 9:39 ` Hannes Reinecke
2024-03-26 9:44 ` Pankaj Raghav
2024-03-26 10:00 ` Hannes Reinecke
2024-03-26 10:06 ` Pankaj Raghav
2024-03-26 10:55 ` Hannes Reinecke [this message]
2024-03-26 13:41 ` Pankaj Raghav (Samsung)
2024-03-26 15:11 ` Pankaj Raghav (Samsung)
2024-03-13 17:02 ` [PATCH v3 05/11] readahead: allocate folios with mapping_min_order in readahead Pankaj Raghav (Samsung)
2024-03-25 19:00 ` Matthew Wilcox
2024-03-26 13:08 ` Pankaj Raghav (Samsung)
2024-04-22 11:03 ` Pankaj Raghav (Samsung)
2024-03-13 17:02 ` [PATCH v3 06/11] readahead: round up file_ra_state->ra_pages to mapping_min_nrpages Pankaj Raghav (Samsung)
2024-03-13 17:02 ` [PATCH v3 07/11] mm: do not split a folio if it has minimum folio order requirement Pankaj Raghav (Samsung)
2024-03-25 19:06 ` Matthew Wilcox
2024-03-26 16:10 ` Pankaj Raghav (Samsung)
2024-03-26 16:23 ` Zi Yan
2024-03-26 16:33 ` Pankaj Raghav
2024-03-26 16:38 ` Zi Yan
2024-03-13 17:02 ` [PATCH v3 08/11] iomap: fix iomap_dio_zero() for fs bs > system page size Pankaj Raghav (Samsung)
2024-03-13 17:02 ` [PATCH v3 09/11] xfs: expose block size in stat Pankaj Raghav (Samsung)
2024-03-13 17:02 ` [PATCH v3 10/11] xfs: make the calculation generic in xfs_sb_validate_fsb_count() Pankaj Raghav (Samsung)
2024-03-25 19:15 ` Matthew Wilcox
2024-03-26 9:53 ` Pankaj Raghav (Samsung)
2024-03-13 17:02 ` [PATCH v3 11/11] xfs: enable block size larger than page size support Pankaj Raghav (Samsung)
2024-03-25 19:19 ` [PATCH v3 00/11] enable bs > ps in XFS Matthew Wilcox
2024-03-26 9:53 ` Hannes Reinecke
2024-03-26 15:06 ` Pankaj Raghav
2024-03-26 14:54 ` Pankaj Raghav (Samsung)
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